1. Field of the Invention
The present invention is related to an airbag system as a safety device for an automobile, and in particular, to an airbag mounting structure by which an airbag system is installed in an automobile using a retainer ring having an air deflector of a simple structure.
2. Discussion of the Related Art
Generally, an airbag system is mounted on a steering wheel or the upper portion of a dash panel of an automotive vehicle, to promote the safety of the driver and possibly another occupant. In such a system, when a sensor detects an abrupt reduction in the vehicle""s traveling speed caused by, for example, a traffic accident, an inflater is activated to introduce high-temperature, pressurized gas into an airbag.
Typically, an airbag system is largely comprised of: an inflater for generating gas very rapidly and expelling the generated gas via a plurality of radially disposed inflation ports to evenly inflate a folded airbag, an operation referred to as xe2x80x9cexplodingxe2x80x9d the inflater; an airbag having an inflater opening for receiving the inflater in order to introduce the gas into the airbag; a baseplate, disposed between the airbag and a flange of the inflater, to which the system components are mounted; and a retainer ring, disposed around the opening and opposing the flange, to hold the system components in place. Each of the system components has a plurality of coupling holes arranged around a central opening or, in the case of the inflater, around the inflater itself. In assembly, the inflater is seated against the bottom of the baseplate so as to protrude through the central openings, and the retainer ring and baseplate are coupled together via the coupling holes to be held tight (clamped) for the life of the airbag system prior to its use, which may be several years. A typical airbag is also provided with a throat portion of a predetermined area extending outward from the opening, which is coupled with a tether to regulate the deployment direction of the airbag. The throat portion includes a reinforced material of a predetermined horizontal tension force, to hold the tether in place upon the exploding of the inflater and to bolster the operation of the retainer ring.
The primary problem present in such an airbag system is that, while in a tightly clamped configuration between the retainer ring and baseplate, the inner edges (perimeter) of the opening of the airbag, facing the centrally mounted inflater, are exposed to the hot gas (e.g., air) rushing out through the inflation ports. Thus, upon exploding the inflater, the opening of the airbag is subject to being burned. A burned or singed airbag opening, particularly one fatigued by a lengthy period in a tightly clamped state, deteriorates the airbag""s operational condition and contributes to a shear stress on the airbag opening introduced due to pulling forces exerted at the coupling points by the rushing gas rapidly filling the airbag, thus degrading performance.
Japanese Patent Laid-open Publication No. hei 3-169765 discloses an airbag system including a rubber collar having an annular fillet disposed around the airbag opening. The rubber collar is placed between the airbag and the retainer ring, such that the annular fillet serves to protect the opening of the airbag from the exploding hot gas. The rubber sheet, however, besides being an additional component which complicates airbag manufacture and increases cost, may exacerbate the shear stress exerted on the airbag opening, due a deformation of the rubber sheet itself, or may loosen the clamping state of the airbag with respect to the baseplate, especially if long-term clamping is to be maintained. Moreover, the annular fillet is ineffective in protecting the edges of the opening of the airbag.
Meanwhile, U.S. Pat. No. 5,368,327 discloses an airbag device for reducing the number of steps needed to manufacture an airbag device while relieving the adverse effects of the shear stress (horizontal tension force) on the airbag. The ""327 patent describes an airbag device in which various protrusions are inserted through intermediately spaced coupling holes, to be displaced by rushing gas and thereby counteract the pulling force caused when the airbag is quickly filled with gas. Though the protrusions can neutralize the horizontal tension force at the opening of the airbag, the opening is still exposed to the hot gas rushing into the airbag from the inflater. Moreover, the airflow into the airbag during rapid inflation is poorly controlled such that skewing may result.
Therefore, it is most appropriate to protect the airbag from the effects of the pressurized, high-temperature gas as well as to neutralize the horizontal tension force.
U.S. Pat. No. 5,836,608 teaches an airbag deflection mount for directing the hot gas into the airbag during inflation, as shown in FIG. 1.
The airbag deflection mount includes a retainer ring comprising: a substantially square outer wall 4 having a coupling hole 3 formed in each corner; an air deflector 2 consisting of a substantially upright inner wall 6 defining an opening 1 for receiving an inflater and twelve equally spaced ears 5 for deflecting air; and a bottom surface 7, connecting the bases of the inner and outer walls, for clamping the collar of the airbag opening in place against the baseplate (not shown). The outer wall slopes away from the opening 1 at an angle of 115xc2x0 with respect to the baseplate, while the deflecting ears 5 slope in the same direction at an angle of 75xc2x0 with respect thereto.
The above-described airbag deflection mount, however, is ineffective in protecting the edges of the opening (throat) of the airbag from the hot gas expelled from the inflater, which is forced out of the inflation ports and against the inner wall, thus coming into contact with the throat and burning the airbag. Most importantly, the airbag deflection mount, with its complex configuration of outer wall and inner wall with multiple deflectors, still fails to deflect large portions of the inflation gas and cannot effectively guide the rushing gas in the desired direction due to the spaces between the ears (deflectors) which produce severe pressure differentials and turbulence. Moreover, such an airbag deflection mount relies heavily on a proper alignment of the ears with respect to the twelve inflation ports of a special inflater, so that a high degree of precision is required for its manufacture.
Accordingly, an object of the present invention is to provide a retainer ring having an air deflector for use with an airbag mounting structure, in which an airbag employed as an automobile safety device is protected from the effects of pressurized, high-temperature gas as well as an adverse horizontal tension force, which are generated upon exploding an inflater.
It is another object of the present invention to provide a retainer ring having an air deflector for use with an airbag mounting structure, in which the configuration of the retainer ring is simplified.
It is a yet another object of the present invention to provide a retainer ring having an air deflector for use with an airbag mounting structure, which prevents the inner edges of the throat of an airbag from being burned by hot gas rushing into the airbag from an inflater.
It is still another object of the present invention to provide a retainer ring having an air deflector for use with an airbag mounting structure, which facilitates the mounting of the airbag as well as the manufacture of its mounting structure.
It is still yet another object of the present invention to provide a retainer ring having an air deflector for use with an airbag mounting structure, which diffuses high-temperature, pressurized gas from an inflater radially and uniformly into the airbag, while preventing the gas from coming into contact with the throat of the airbag.
It is a further object of the present invention to provide a retainer ring having an air deflector for use with an airbag mounting structure, which provides a simplified alignment means for the mounting of the airbag system to a supported baseplate.
It is yet a further object of the present invention to provide an airbag mounting structure suitable for use with the retainer ring.
To achieve these and other advantages and in accordance with the purposed of the present invention, as embodied and broadly described herein, there is provided a retainer ring having an air deflector, for use with an airbag mounting structure, the retainer ring comprising: an upper flange in which an inflater opening for receiving an inflater is formed; and a wall, a base of which is connected to the upper flange, extending upward and outward from the inflater opening at a predetermined angle to diffuse and deflect exploding gas upward.
According to another aspect of the present invention there is also provided an airbag mounting structure comprising: an inflater including a plurality of inflation ports provided on a main body thereof and arranged around the circumference of the main body, and a lower flange in which a plurality of first coupling holes and an alignment notch are formed at predetermined positions; a baseplate in which a first circular opening is formed to seat the main body of the inflater, a plurality of second coupling holes and a first alignment hole, corresponding to the first coupling holes, being formed in the baseplate around the first circular opening; an airbag, in which a second circular opening is formed to receive the main body of the inflater, having a mounting surface provided around the second circular opening, in which a plurality of third coupling holes and a second alignment hole, corresponding to the first and second coupling holes and the first alignment hole, respectively, are formed; and a retainer ring in which a third circular opening is formed to receive the main body of the inflater, a plurality of fourth coupling holes and a third alignment hole being formed in an upper flange to correspond to the first, second, and third coupling holes and the first and second alignment holes, respectively, the retainer ring including an integrally formed air deflector and a tabbed cut-out juxtaposed to one of the fourth coupling holes, the tabbed cut-out being bent at a right angle. In the above structure, the tabbed cut-out passes through the alignment notch and the first, second, and third alignment holes during assembly, to determine a mounting position and orientation.
In a preferred embodiment, the airbag mounting structure further comprises a plurality of semi-circular convex portions projecting inwardly towards the inflater opening. The convex portions are regularly spaced around the circumference of the wall at positions corresponding to the first through fourth coupling holes and abutting a surface of the main body of the inflater when the inflater is seated with the baseplate, to thereby support the main body of the inflater.
In another preferred embodiment, the airbag mounting structure further comprises a plurality of rib formations integrally formed on an inner side of the wall between the convex portions. The rib formations are evenly spaced, as a pair of rows covering the height of the inner side of the wall, and slope downward on either side of the convex portions, to thereby block hot air from coming into contact with the airbag.
Therefore, according to the present invention, an airbag mounting structure comprises a retainer ring having an air deflector which directs the expelled gas into the airbag, while sustaining a horizontal tension force during inflation, to effectively prevent the hot gas from burning the throat of the airbag.